Industrial robot system

ABSTRACT

The present invention relates to an industrial robot comprising a manipulator ( 2 ), a control unit ( 3 ) for controlling the manipulator, a portable operating unit ( 4 ) for teaching an manually operating the robot, which operating unit is adapted for wireless communication with the control unit and comprising a operator control means ( 9 ). The invention increases the safety by ensuring that the operator is within the specified operating area.

TECHNICAL FIELD

The present invention relates to an industrial robot system, including amanipulator and a control unit having means for automatically operatingthe manipulator. A portable operator control device is connected to thecontrol unit having means for teaching and manually operating themanipulator. The invention also relates to a method for controlling anindustrial robot system. Especially the invention relates to acommunication control. Particularly the invention relates to a wirelessteach pendant unit.

An operator control device is a portable operator control device denoteda teach pendant unit, TPU, in the following. A TPU normally comprisesoperator control means and a visual display unit. The operator controlmeans usually is a joystick, a ball, a set of buttons or any combinationof these.

BACKGROUND OF THE INVENTION

An industrial robot is programmed to carry out work or a work cyclealong an operating path. In order to program or teach the robot the workcycle, the robot is manipulated to positions along the desired operatingpath. These positions are stored as instructions in a memory in thecontrol unit. Other information, such as desired robot movementvelocity, may also be stored in the memory. During operation of therobot, the program instructions are executed, thereby making the robotoperate as desired.

A robot is operated in at least two modes: automatic and manual. Byswitching a mode selector key on a control panel on the control unit,the choice of mode, in which the robot shall operate, is made. When therobot is in the manual mode, the TPU has the exclusive right to operatethe robot and thus no other operating control device or control unit isallowed to control the robot.

An industrial robot is usually placed in robot cells in order tofacilitate the automation of a complex series of actions under safeconditions. When one of the robots in a robot cell is to be operatedunder manual control using a TPU, it is important that the TPU iscommunicating with and controlling the right robot. Thus, in order toaccomplish a safe control of an industrial robot, it is important tohave absolute confidence in the control of the robot. The operator mustbe fully aware of the current mode of the connection between the controlunit and the TPU.

In an industrial robot system where the TPU is connected to the controlunit by a cable, the operator can easily be aware of the current mode ofsaid connection. The cable is preferably shielded and no othercommunication systems can interfere with the two connected units. Undernormal conditions the control unit periodically transmits data to theTPU. Upon receiving this data the TPU responds by transmitting aresponse signal back to the control unit. Thus, the control unit asksthe TPU if this is in operation. The control unit judges from saidresponse signal if the TPU is in normal condition. If the emergencyswitch has been activated, the response signal carries that informationand the control unit executes the emergency stop. The length of thecable defines the maximum distance between a TPU cable connected to anindustrial robot and the control unit.

In an abnormal situation, e.g. when the operating unit is disconnectedor the cable is cut off, the TPU does not transmit a responding signal.The absence of a responding signal is a sign to the control unit thatthere is an emergency stop situation and the control unit will activatethe emergency stop.

However, the TPU cable ends up entangled on the floor in industrialrobot systems with several robots and hence several cables. The cablesare often lying on the floor and there is an obvious risk of damage by avehicle running over. There is also a risk of cable entanglement bywhich an operator will have difficulties in knowing which TPU belongs towhich robot. Furthermore, a TPU connected by cable to a control unitlimits the degree of freedom that an operator needs to perform aneffective operation with the robot.

In accordance with the conditions mentioned above, the development ofindustrial robot systems is in one way leading to a wireless TPU for therobot control. A wireless connection eliminates most of the negativeconsequences of using a cable connection. On the other hand, a wirelessconnection introduces some problems of its own. Most notable is theproblem of ensuring that the TPU is associated with the correct robotand the problem of verifying that the wireless connection workscorrectly.

In both cases, there is a risk of personal injury if the operatorbelieves that he is operating and controlling a certain robot butinstead is out of contact with this particular robot. Thus, there is astrong need to ensure connection between the robot and the TPU whenusing a TPU not physically connected to the robot. In other words, it isof great importance that the operator is immediately made aware of asudden communication loss of the TPU. Since the operator usually isconcentrated on the robot and there may be a great deal of ambientnoise, the usual warnings (blinking light, buzzer) are ineffective andnot reliable.

One security arrangement in an industrial robot system with a robotworking in a cell is designed as follows. If something abnormal happensin the cell, an operation stop is activated and the operating robot isstopped and remains standing still. After reestablishment of a normalcondition in the cell, the robot will be restarted. In this situation, astopped robot does not disturb the rest of the robot system. Then, thereis a higher degree of security stop and that is the emergency stop forstopping the whole robot system. This is activated when somethingextraordinary happens somewhere in the robot system. Closing down thewhole robot system is undesirable since it necessitates a great deal ofwork for the operator to return the system to operation conditions.

From the Japanese patent application 11-73201, a wireless control systemis previously known. The object of the invention is to provide acommunication system wherein the specific communication of emergencystop control can be carried out by wireless means in a manner equivalentto cable communication. The solution of the invention is in the designof the system with data exchange by means of wireless or opticalcommunication between a first device and a second device. The firstdevice comprises a transmitting part and a receiving part. The seconddevice comprises a receiving part and a transmitting part, which returnsarbitrary data in response to data received from said first device at anormal time, and stops said response at an abnormal condition. The firstdevice judges the condition to be abnormal by recognizing the receiveddata to be arbitrary data. It also judges the condition to be normal byrecognizing the received data to be specific data. Thus, specificcommunications such as emergency stop control is carried out by wirelessmeans in a manner equivalent to the prior cable communication, and thesystem is made fail-safe.

A wireless connection is less predictable than a wired connection, andthe communication between the TPU and the control unit may fail, beloosen or be broken by the system due to either distance, signalinterference, radio shadow, current interruptions or battery failure,all of which will cause a communication loss. All differentcommunication losses are denoted “a broken data link” and all differentoperating communications are denoted “a connected data link” in thefollowing.

If a broken data link occurs, arrangements required by safetyregulations will immediately stop the robot. These security arrangementsare further programmed to measure the time for the robot standing stillin accordance with the situation mentioned above. When the robot hasbeen standing still for a predetermined time due to the broken datalink, the emergency stop is activated and all activities in the cellwill be stopped. The time between these events is chosen in order tocomply with the safety regulations in force.

Despite necessity of security systems, a sudden shutdown of a robotsystem is a very frustrating situation for the operator. It requirestime and energy for realizing the situation. It also takes a great dealof effort and time to reestablish the working condition in the robotsystem. This is a situation every operator is anxious to avoid,especially when there is no reason for the stop.

According to the conditions mentioned above, there is a need for anindustrial robot system including a TPU, which system has the functionof immediately making an operator aware of a broken data link. Moreprecisely, there is a need for a TPU, which has the character ofimmediately indicating a broken data link to an operator carrying theTPU.

SUMMARY OF THE INVENTION

The object of the invention is to provide an industrial robot system,which makes it possible for an operator carrying a portable TPUconnected to the system to work in an increased operation area, flexiblyand effectively without being worried about where the position of theTPU. A second object of the invention is to facilitate the work with aportable TPU, for operating an industrial robot system, defined aboveand additionally to avoid unnecessary emergency stops.

These objects are achieved according to the invention in a first aspectwith an industrial robot system comprising the characteristic featuresof the independent claim 1, in a second aspect with a method forcontrolling an industrial robot system comprising the characteristicfeatures of the independent method claim 14. According to the invention,these objects also are achieved in a data program product comprising thecharacteristic features of the independent claim 23, and a use of themethod according to claims 26. Preferred embodiments are described inthe dependent claims.

According to the invention, one or a plurality of robots are controlledby one TPU unit. Each TPU is communicating with the control unitlocally. There is a limit built into the system as to how far from thecontrol unit a TPU is allowed to operate. Thus, there is a maximumoperating distance for the TPU, which distance usually varies indifferent directions around the control unit. Often, the maximumdistance comprises intervals defined not to allow operation. Therefore,distances together with directions define one or a plurality of workareas A within which the TPU is allowed connection to the control unitunder secure conditions. These distances, directions and defined areasare invisible but an important security limitation since an operator hasdifficulties in knowing where to be positioned.

When an activated TPU is moved away from the control unit longer thanthe mentioned maximum operating distance, the system is programmed tobreak the connection to the control unit. Thus, if an operator, bringinga wireless TPU connected to the robot, is walking too far away from thecontrol unit, the control unit will break the data link to the TPU. Thedata link will also be broken when the TPU positioned in a defined workarea A suddenly passes the border into the exterior area. Thus, it is anobject of the invention to connect/disconnect a TPU due to the exactposition of the TPU. Therefore, the position determining means accordingto the invention is provided to operate with a high degree of accuracywith the result that the exactness of the safety in the robot systemincreases desirably.

The solution according to the first aspect of the invention is toprovide an industrial robot system with at least one industrial robotcomprising a manipulator, a control unit comprising a processor forcontrolling the manipulator, a portable operator control device, TPU,for teaching and manually operating the robot. The system comprisesmeans provided to determine the exact position of the TPU.

According to the invention, the position determining means comprises areference station including means for sending a signal to the TPU, wherethe TPU is arranged to retransmit a reply signal. The positiondetermining means further comprises at least one receiving means, forreceiving the transmitted reply signal from the TPU.

In one embodiment of the invention, the position determining meanscomprises means for measuring time. A signal is transmitted from areference station comprising means for transmitting and receiving asignal and the time measuring means. According to the invention, thetime measuring means is measuring a time interval starting when thesignal is sent to the TPU and ending when receiving the retransmittedreply signal from the TPU. In this embodiment, the reference stationincludes a radio tower and the receiving means includes an antennameans.

In another embodiment of the invention, the position determining meansis arranged to measure angle/direction. Two reference stations, providedwith receiving means, are sending signals to the TPU and receive theretransmitted reply signal from the TPU. The position of the TPU is thenobtained by triangulation.

In another embodiment of the invention, the position determining meansis arranged to measure distance. Two reference stations, submitted inaccordance with the previous embodiment, are sending signals to the TPUand are further provided for determining their respective distance tothe TPU. The position of the TPU is determined on the basis of themeasured distances and a calculated intersection point.

According to the invention, the position determining means is measuringdistance, direction or a combination of distance and direction. It ispossible to simplify the position determining problem to atwo-dimensional problem, which can be applicable to a robot operator. Byadding a third reference station, the positing is done in athree-dimensional space. This combined solution has the added benefitthat only one reference station is needed.

According to the invention, indicating means is arranged in the TPU forindicating to the operator that the TPU is positioned outside thedefined area A and consequently that the data link is broken. Theindicating means indicates the broken data link through tactile feedbackby touch perception to the body of the operator. According to theinvention, the indicating means is either an active or a passiveindicating means. The operator is usually carrying the TPU and both theactive and passive indication through physical perception is a tactilefeedback to the hand.

An active indicating means is defined to create a mechanical force,which transfers information to an operator, without the operator askingfor it. In one embodiment of the invention, the active indicating meanscomprises vibrating means operable to vibrate due to a broken data link.In another embodiment, the vibrating means is included in the TPU. Inanother embodiment, he vibrating means is included in an operatorcontrol means. According to the invention, the operator control means isa joystick operable to vibrate due to a broken data link. In yet anotherembodiment of the invention, the active indicating means is arranged toindicate by means of light, sound or a combination thereof.

A passive indicating means is defined to create a mechanical movementreaction, which is arranged to be stiffer or looser upon indication.According the invention, the passive indicating means is included in anoperator control means. In one embodiment, the operator control isarranged to introduce a mechanical resistance to movement duringoperation, when the data link is communicating in a normal way. Upon abroken data link, the passive indicating means is arranged to loosen theresistance to movement in the operator control means. In one embodimentof the invention, the operator control means is a joystick and thepassive indicating means comprises resilient means operable to introducea mechanical resistance to manual movement of the joystick. A passiveindication includes a mechanical movement reaction created by looseningthe mechanical resistance.

The solution according to the second aspect of the invention is toprovide a method for control of an industrial robot system with anindustrial robot comprising a manipulator, a control unit comprising aprocessor and a portable TPU. The TPU communicates with the control unitvia a data link for manually programming and operating the manipulator.One or a plurality of work areas A is defined for the TPU. Positiondetermining means determine the exact position of the TPU. The robotcontrol system is programmed to break the data link when the TPU isdetermined to be positioned outside the work area A and programmed tocontinue the data link communication when the TPU is determined to bepositioned within the work area A.

According to the invention, the position of the TPU is determinedcontinuously on the basis of a signal sent to the TPU from at least onereference station comprised in the position determining means. Thesignal is retransmitted from the TPU in the form of a reply signal,which is received by at least one receiving means comprised in theposition determining means.

In one embodiment of the invention, the position determining means isbrought to measure the time interval between sending a signal andreceiving the transmitted reply signal.

In another embodiment of the invention, the position determining meansis brought to measure the respective distance between the TPU and twoseparate reference stations by means of retransmitted reply signals fromthe TPU.

In yet another embodiment of the invention, the position determiningmeans is brought to measure the respective direction between the TPU andtwo separate reference stations by means of retransmitted reply signalsfrom the TPU.

In yet another embodiment of the invention, the position determiningmeans is brought to measure both the distance and the direction betweenthe TPU and a single reference station by means of a retransmitted replysignal from the TPU.

According to the invention, the position of the TPU is determinedcontinuously.

According to one embodiment of the invention, the data link in theindustrial robot system is a wireless data link. In another embodimentof the invention, the link is a radio link connected to andcommunicating through a network. In yet another embodiment, the TPUcomprises a unit sold under the name of Bluetooth.

For a wireless TPU the enforcement of the work area is not easy.According to the invention, a wireless positioning system, radio basedor otherwise, is used to locate the wireless TPU and its operator andthereby enforce the applicable work area. The positioning system is aseparate system or an integral part of the radio communication systemused by the wireless TPU for normal operation and emergency stopcommands.

In one embodiment of the invention, the data link is operable due toboth a steady stream of command messages from the control unit to theTPU and messages in response from the TPU back to the control unit. Thecontrol unit is operable to break the data link through breaking thestream of command messages.

In another embodiment of the invention, the data link is operable due toboth a steady stream of command messages from the TPU to the controlunit and messages in response from the control unit to the TPU. Theindustrial robot system is operable to break the data link throughbreaking the stream of response messages.

In yet another embodiment of the invention, the industrial robot systemis operable to break the data link through an instruction from thecontrol unit.

According to the invention, the physical medium for the positioningsystem is sound, ultrasound, light or electromagnetic radiation.

According to the methods mentioned above, a broken data link is due to abroken stream of command messages or is due to a broken stream ofresponse messages. In another method according to the invention, thedata link is broken due to an instruction from the control unit.

The security arrangements are programmed to in some way accept the TPUgetting closer to the control unit within said chosen time limit.Consequently, if the TPU comes close enough to the control unit, oralternatively enters a work area A in due time, the operation stop willbe reset and the robot reactivated. According to the invention, thedisplay of the TPU gives information to the operator concerning thereason for a broken data link. In one embodiment, the display alsoinforms the operator in which direction he and the TPU shall move forentering the area A. Then, the operator has the possibility to move fastinto the area A and thereby avoiding a sudden shutdown of the robotsystem. The solution according to the invention increases the accuracyof the control of the industrial robot system.

According to the invention, the position determining means is arrangedto operate in a whole factory or in a smaller area within the factory.Furthermore, the position determining means comprises at least on e roofmounted receiving means for determining the position of the TPU in threedimensions.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be explained in more detail by the description ofdifferent embodiments thereof and with reference to the appendeddrawings in which:

FIG. 1 is a wireless communication system according to the invention,

FIG. 2 is a position determining means, in accordance with theinvention, comprising four reference stations, one of which comprises atransmitter,

FIG. 3 is a position determining means, in accordance with theinvention, comprising two reference stations measuring direction,

FIG. 4 is a position determining means, in accordance with theinvention, comprising two reference stations measuring distance,

FIG. 5 is a position determining means, in accordance with theinvention, comprising one reference station measuring both direction anddistance.

FIG. 6 is a TPU according to the invention.

FIG. 7 is a schematic cross section of a joystick comprising a resilientmeans including a regulating means creating mechanical resistance tomovement of the joystick.

FIG. 8 shows the joystick in FIG. 7 in a relaxed position lackingmechanical resistance to movement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a communication system comprising an industrial robot 1,including a manipulator 2 and a control unit 3 for controlling themanipulator. A TPU 4, for teaching and manually operating themanipulator, is communicating with the control unit 3 via a wirelessdata link 5. The TPU includes an antenna 6 for wireless communicationwith the control unit 3.

In FIG. 2, the position determining means 7 comprises a referencestation 8 including a first radio tower 9 and means for measuring time13 a. Another three radio towers 10, 11 and 12 are arranged at adistance from each other and from the reference station 8. Each radiotower 9, 10, 11 and 12, respectively, comprises a signal receiving means14, 15, 16 and 17, respectively. A signal 18 is sent to the TPU 4 from atransmitter 19 arranged in the reference station 8. The time measuringmeans 13 a is measuring a time interval starting when the signal 18 issent to the TPU 4 and ending when the respective receiving means 14, 15,16 and 17 receive a retransmitted reply signal 20, 21, 22 and 23,respectively, from the TPU 4 in accordance with the following.

The reference station 8 includes the transmitter 19 for sending a radiosignal 18 to the TPU. The TPU receives the signal 18 and retransmits areply signal 20, 21, 22 and 23 to the four radio towers and respectivesignal receiving means 14, 15, 16 and 17.

The first radio tower 9 comprises the signal receiving means 14, whichreceives the retransmitted reply signal 20. The second radio tower 10 isconnected by a radio link H to the first radio tower 9 and transmits thereply signal 21 on the link H to the first radio tower 9. The thirdradio tower 11 is connected by a radio link Z to the first radio tower 9and transmits the reply signal 22 on the link Z to the first radio tower9. The fourth radio tower 12 is connected by a radio link W to the firstradio tower 9 and transmits the reply signal 23 on the link W to thefirst radio tower 9.

A set of high-speed timers 24, 25, 26 and 27 is arranged in the firstradio tower 9 and are activated simultaneously when a signal 18 istransmitted to the TPU. The signal 18 is retransmitted by the replysignals 20, 21, 22 and 23 received at respective radio towers 10, 1-1and 12. The reply signals 21, 22 and 23 are then transmitted via therespective radio links to the reference station 8. The timer 24, 25, 26and 27, respectively is stopped when is has registered the correspondingreply signal 20, 21, 22 and 23. The position of the TPU is thencalculated on the basis of the known parameters for the positions of thefour radio towers and the speed of the signal propagation in combinationwith the measured time intervals. In this embodiment, the time measuringmeans are synchronized. In FIG. 2, the four radio towers are arrangedforming a rectangle and this is one embodiment of the invention. Thisarrangement also gives the possibility to determine the position of theTPU in two or three dimensions.

According to the invention, one alternative is an arrangement with onereference station and two radio towers, which provides the possibilityto determine the position of the TPU in two dimensions. In FIG. 3 tworeference stations 28 and 29 are arranged separated from each other. Therespective reference station 28, 29 comprises receiving means 30, 31,each including an antenna means 32. The reference station 28 and 29,respectively, is arranged to transmit a signal 33 and 34, respectively,to the TPU 4 and measuring means 13 b measure the angle/direction ofrespective retransmitted reply signals 35 and 36 from the TPU. In oneembodiment, the two reference stations 28 and 29 are transmitting at twodifferent frequencies. The position of the TPU is then obtained bytriangulation. The position determining means is determining theposition of the TPU in three dimensions when a third reference stationis provided for (not shown).

FIG. 4 is the same embodiment as FIG. 3 except for one difference: theposition of the TPU is determined by measuring the distance between theTPU and the respective reference station. The position is obtained bythe intersection of two circles, each around the respective referencestation, which has the measure distance as the radius. The distances canbe measured by the time of the arrival of a retransmitted reply signalsent by the TPU, if the TPU and the reference stations are synchronized.The time of arrival can be converted into distance since the speed ofthe signal propagation is known. In another embodiment, the distance isobtained by measuring the round-trip delays. The position determiningmeans 7 is determining the position of the TPU in three dimensions whena third reference station is provided for (not shown).

FIG. 5 shows in the two-dimensional case where the position of the TPUis determined by combining the two methods described in FIGS. 3 and 4.

The control of the industrial robot system, defined above, is operatedas follows. One or a plurality of work areas A are defined for the TPUand the corresponding data information is programmed and stored in theprocessor of the control unit 37. The position determining means 7determines the position of the TPU 4 and the corresponding informationis stored in the processor 37. The processor is provided to compare theposition of the TPU with the position of a work area A. The processor 37is further provided to break the data link 5 when the TPU 4 ispositioned outside the work area A. Further, the processor 37 isprovided to continue communication of the data link when the TPU ispositioned within the work area A.

FIG. 6 is a TPU 4 according to the invention. The TPU 4 comprises aportable box 38 including a display means 39, function keys 40, ajoystick 41, indicating means 42 and an emergency stop device 43. TheTPU includes an antenna 44 for wireless communication with the controlunit 3. The indicating means 42 is arranged to actively or passivelyindicate to the operator a broken data link 5. The TPU comprises activeindicating means 45, which comprises vibrating means 46, arranged,integrated into the TPU 4. Upon a broken data link 5, the activeindicating means 45 is activated and the vibrating means 46 starts tovibrate. This vibration is, during operation, an active indication tothe operator that the data link 5 is broken. This tactile feedback isbrought by touch perception to the body 47 of an operator bringing theTPU 4. In one embodiment of the invention, the active indicating means45 comprises vibrating means 46 arranged integrated into a joystick 41(not shown).

The reference station comprises an antenna means. According to theinvention, the antenna means comprises a beam-shaped antenna, asteerable antenna or an antenna with multiple receiving elements, whichmeasure the relative phase between the elements (not shown).

According to the invention, a joystick comprises passive indicatingmeans. The passive indicating mean is integrated into the joystick andis arranged to introduce a mechanical resistance to manual movement ofthe joystick. The passive indicating means comprises resilient meansarranged to passively indicate to the operator a broken data link by amechanical movement reaction created by loosening or stiffening themechanical resistance.

FIG. 7 is a joystick 41, which comprises one helical spring 49 arrangedvertically and provided with a thread 50 connecting the helical springand a resilience control means 51. In this embodiment, the mechanicalresistance to movement is provided for by means of only one helicalspring. In FIG. 7 the joystick is arranged to create a mechanicalmovement reaction, which is arranged to be looser upon indication abroken data link 5. In FIG. 8, the joystick 41 is indicating a brokendata link 5 through the relaxed thread 50. In another embodiment of theinvention, a joystick comprises

While only certain preferred features of the present invention have beenillustrated and described, many modifications and changes will beapparent to those skilled in the art. It is therefore to be understoodthat all such modifications and changes of the present invention fallwithin the scope of the claims.

1. Industrial robot system, with an industrial robot comprising amanipulator, a control unit for controlling the manipulator, at leastone portable operator control device, TPU, for teaching and manuallyoperating the robot, which TPU is adapted for communication with thecontrol unit through a data link the system comprising: a definedworking area for the TPU, means to determine the position of the TPU,and the system is provided to connect/disconnect the data link such thatthe data link is broken/disconnected upon the TPU being outside thedefined working area, or the data link is connected upon the TPU beinginside the working area.
 2. The industrial robot system according toclaim 1, wherein the position determining means comprises at least onereference station arranged to send a radio signal to the TPU.
 3. Theindustrial robot system according to claim 1, wherein the positiondetermining means comprises at least one receiving means for receiving atransmitted reply signal from the TPU.
 4. The industrial robot systemaccording to claim 3, wherein the receiving means comprises antennameans.
 5. The industrial robot system according to claims 3 and 4,wherein the reference station comprises the receiving means.
 6. Theindustrial robot system according to claim 1, wherein the control unitis operable to define a work area.
 7. The industrial robot systemaccording to claim 1, wherein the position determining means comprisesmeans for measuring the time between transmitting the signal andreceiving the reply signal.
 8. The industrial robot system according toclaim 1, wherein the position determining means comprises means formeasuring direction/angle between the transmitted signal and thereceived reply signal.
 9. The industrial robot system according to claim1, wherein the robot system comprises indicating means for indicatingthe current mode of the data link.
 10. The industrial robot systemaccording to claim 9, wherein the indicating means is operable tophysically indicate a communication failure of the data link throughtactile feedback by touch perception to the body of an operator bringingthe operator control device during operation.
 11. The industrial robotsystem according to claim 10, wherein the indicating means is arrangedto indicate actively through vibrations.
 12. The industrial robot systemaccording to claim 10, wherein the indicating means is arranged toindicate passively through resilient means operable to introduce amechanical resistance to movement of an operator control means.
 13. Theindustrial robot system according to claim 1, wherein the data link is awireless data link.
 14. A method for controlling an industrial robotsystem, with an industrial robot comprising a manipulator, a controlunit comprising a processor for controlling the manipulator, at leastone portable operator control device, TPU, for teaching and manuallyoperating the robot, which TPU is adapted for communication with thecontrol unit via a data link, the method comprising: defining a workingarea for the TPU, determining the position of the TPU, upon the TPUbeing outside the working area, conduct a broken the data link, upon theTPU being inside the working area, conduct a connected data link. 15.The method according to claim 14, wherein positions determining means isbrought to send a signal to the TPU.
 16. The method according to claim15, wherein the positions determining means is brought to receive atleast one transmitted reply signal from the TPU.
 17. The methodaccording to claim 16, wherein the position measuring means is broughtto measure the time between transmitting the signal and receiving thetransmitted reply signal.
 18. The method according to claim 16, whereinthe position determining means is brought to measure the distancebetween the TPU and the reference station.
 19. The method according toclaim 16, wherein the position determining means is brought to measurethe direction between the TPU and the reference stations.
 20. The methodaccording to claim 16, wherein the position determining means is broughtto measure both the direction and the distance between the TPU and thereference station.
 21. The method according to claim 14, wherein theposition of the TPU is determined continuously.
 22. The method accordingto claim 14, wherein the control unit is operable to break the datalink.
 23. A computer program product comprising instructions to beeffectuated by a processor to control an industrial robot system inaccordance with the method according to claim
 14. 24. The computerprogram product according to claim 23 at least partly supplied over anetwork such as the Internet.
 25. A computer readable medium containinga computer program product 24 according to claim 23.